In the vast array of electrical properties that constitute a signal, it is impractical to employ one electrical interface that accepts every signal for processing. Instead, signal detectors and signal converters are used in specific ways to interface specific signals for specific processes. Comparators are devices used to judge one input against another to produce an output. In the domain of logical ones and zeros, a process judges one digital word against another to yield an output signifying that one input is GREATER than, EQUAL, or LESS than the other. For analog signals however, a comparator more accurately refers to a level detection device, or biased differential amplifier, that derives an output by comparing a known reference value to a signal source. Comparators often convert analog signals into digital values through various prior art techniques frequently employed as intermediate elements in a system between an input and a process to interpret signals. Although comparators represent distinct functions within digital or analog processes, both arrangements in a plurality of logical outputs produce raw data elements used to facilitate other circuits, devices, or processes.
U.S. Pat. No. 7,046,180 filed by Jongsma, et al., granted May 16, 2006, presents a system that requires a specifically configured analog encoding system using a combination of scaling, inversion and level shifting to produce non-overlapping encoded values with unique ranges for detecting specific fault conditions while processing a plurality of decoded data elements for quantifying signals. Generated across a resistive network switched from a control circuit, course and fine reference voltages are used to bias an analog-to-digital converter for separating data elements from non-overlapping encoded signal values. Decoded data elements are then compared to a sequence of stored reference values in memory to determine actual signal and fault conditions. Before processing the original source signal, encoded non-overlapping ranges have to be converted from scaling, inversion and level shifting back into intelligible signal or data elements. The process presented requires both an encoder and a decoder to implement requiring multiple analog reference voltages to achieve.
Utilizing scaling, inversion and level shifting techniques involve additional processes separate and distinct from techniques generally considered for simply converting signals from analog to digital values. Although the system produces some benefit for identifying specific fault conditions, it should be obvious to one of ordinary skill in the art that multiple conversions are needed to first encode a signal into non-overlapping values at one stage of a conversion process and then reproduce the original signal in digital form for further processing at another. This two stage approach constitutes more components and/or more process time than simply converting signals from analog to digital values.
Furthermore, utilizing reference voltages to decompress or separate data elements from encoded values introduce accuracy and tolerance issues requiring the use of more expensive components such as precision voltage reference generators and/or precision resistive voltage dividers. Switching methods described for generating multiple voltage references are particularly sensitive to temperature changes which can have an appreciable affect on both reference baseline values and decompressed data elements. Moreover, utilizing a sequence of unique values stored in memory for determining signal elements also contributes to slower response time and memory consumption.
An integrated circuit is presented in U.S. Pat. No. 7,057,422 filed by Berg, granted on Jun. 6, 2006, that regulates the operating point of an external circuit through the use of an analog to digital conversion process. The approach utilizes the output of an analog comparator to control the count direction of clock cycles in the first of two counters while advancing the count of the second counter to vary voltage levels used by the analog comparator to judge against a voltage reference in a conversion process. The content of the first counter represents a data conversion value that is then locked in from further changes allowing stable control over voltage levels affecting the operation of the analog comparator. A locking circuit that isolates electrical chatter enhances a common tracking ADC conversion process or logic “racing” otherwise produced by count direction changes. The locking circuit inherently provides some intrinsic stability against signal transients and noise. Any stability gained against signal transients and noise however, is a strictly incidental benefit of the locking circuit's performance to remove logic racing from the first counter tracking the analog converter's output. To preserve the highest possible resolution of the circuit, it would be reasonable to lock in the value of the first counter just prior to (or just after) a change in count direction. Locking in the value of the first counter accounts for one (least significant) bit of a data word produced by the conversion process for protection against transient signals and noises. In a 2-bit word, for example, the protection offered by a circuit would be limited to one fourth of the signal magnitude. Using an 8-bit word for higher resolution would effectively render the protection against transient signals and noises useless.
What is needed is a system to apply a filtering process that would eliminate the need for logic comparisons between source and reference signals and a method to produce, store, and retrieve specific information based upon a configuration of re-definable filter variables. The filtering process could be used to extract undesirable elements from a reference signal to provide protection against transient signals and noises while at the same time increasing the sensitivity to small signal changes. The process could also be used to extract desirable signal elements for characterizing a digital pattern, an analog value, signal status, or the detection of specific signal changes. Moreover, a system is needed to organize information for immediate access by internal and external processes reliant upon configurable aspects from specific signal sources.